Lifting device



J. B. M ALPINE LIFIING DEVICE Sept. 21, 1965 3 Sheets-Sheet 1 Original Filed Sept. 20, 1960 Se t. 21, 1965 J. a. M ALPINE 3,207,046

LIFTING DEVICE Original Filed Sept. 20. 1960 5 Sheets-Sheet 2 j g y 0 J. B. M ALPINE LIFTING DEVICE Sept. 21, 1965 3 Sheets-Sheet 3 Original Filed Sept. 20. 1960 United States Patent O 3,207,046 LIFTING DEVICE John B. McAlpine, Scarborough, Ontario, Canada, as-

signor to Symington Wayne Corporation, Salisbury, Md., a corporation of Maryland Original application Sept. 20, 1960, Ser. No. 57,325, now Patent No. 3,141,390, dated July 21, 1964. Divided and this application Aug. 13, 1963, Ser. No. 311,270 Claims. (Cl. 92-59) This is a division of application Serial No. 57,325, filed September 20, 1960, now Patent Number 3,141,390, granted July 21, 1964.

This invention relates to a lifting device for carrying a relatively high load through a relatively long working stroke, and it more particularly relates to such a device which can raise and lower a long and heavy aircraft engine through a stroke substantially equal to its length to make it completely accessible from a given working level.

Modern aircraft engines, for example, of the pure jet type, are quite long and heavy, and it is difiicult to obtain complete access to them when they are dismounted for maintenance. Ordinarily elaborate staging is used which must be assembled and disassembled. Proposals have, therefore, been made to raise and lower these engines upon a lifting platform mounted within a pit past workmen at ground level to make any part of the engine easily available without requiring precarious scaffolds or stages. However, jet engines are quite long and heavy which imposes a severe load upon a hydraulic lift. Furthermore, a single plunger is highly susceptible to damaging oscillation under load when it is extended in the range of six feet which offers quite a severe problem when a delicate and expensive mechanism, such as a jet engine, is being handled. Were expense of no importance, a suitable lift could be made by increasing the size of all the parts and using the strongest materials. However, this use of special materials and structural shapes would be prohibitively expensive.

An object of this invention is to provide a simple and economical lifting device which is capable of carrying relatively great loads through a relatively long working stroke with minimum oscillation characteristics.

Another object is to provide such a device which incorporates a plunger and cylinder which are simple and economical to manufacture, assemble, install and remove for maintenance.

Still another object is to provide such a plunger and cylinder which utilize commercially-available structural materials; and

A further object is to provide such a device which is safe and positive in operation.

In accordance with this invention a remarkably strong plunger with minimum oscillation characteristics for a lifting device can be made from commercially-available structural materials by inserting a number of slender rods within an elongated tube, made for example of standard steel tubing, and welding the ends of these rods, which may be concrete reinforcing rods made of steel, to the ends of the inner wall of the casing to increase its tensional strength. The casing is then filled with a cementitious mixture such as concrete to make it remarkably strong in compression and resistant to oscillation.

3,207,046 Patented Sept. 21, 1965 ice A remarkably simple and conveniently assembled and disassembled cylinder for a lifting device incorporates a pair of longitudinally aligned tubular sections joined with an internal bearing ring held between them. The joinder between these sections is particularly conveniently accomplished by connecting a pair of flanges upon the tubular sections to a peripheral flange upon the bearing ring. Peripheral seals, such as O-rings, are utilized between the bearing and inner cylinder wall to have metal to metal contact between the flanges, insure alignment between the tubes upon assembly.

A highly convenient means for connecting the cylinder for such a lifting device to a foundation is provided by an auxiliary base plate which is aligned with the base of the cylinder by a sliding centering means and temporarily attached to it by breakable straps, which hold the parts together prior to securing the base plate to the concrete foundation. This facilitates withdrawal of the cylinder from the foundation structure whenever necessary.

An unusually simple and effective resilient pawl type of safety device, for preventing the platform from dropping in the absence of hydraulic pressure, is provided by a pneumatic piston and cylinder incorporating an annular piston whose force is transmitted to the pawl through a sleeve-contained compression spring. Furthermore, a positive acting high liquid level float-operated valve for an accumulator tank used with such a lifting device is provided by employing a restrictive passageway which builds up gas pressure within the accumulator tank immediately prior to closure to insure the provision of a positive valve-closing differential.

Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:

FIG. 1 is a cross-sectional view in elevation of one embodiment of this invention carrying a jet engine;

FIG. 2 is a plan view of the embodiment shown in FIG. 1 with jet engine removed and lifting platform in phantom;

FIG. 3 is a cross-sectional view taken through FIG. 2 along the line 3-3;

FIG. 4 is a plan view of the cylinder and plunger assembly shown in FIG. 1;

FIG. 5 is a cross-sectional view taken through FIG. 4 along the line 55;

FIG. 6 is a cross-sectional view taken through FIG. 5 along the line 66.

In FIGS. l-3 is shown a hydraulic lift assembly 10 carrying a load such as a jet engine 12 upon a platform 14 which is raised and lowered by upward and downward movement of a plunger 16 within a cylinder 18. Cylinder 18 is accommodated within a well 20 enclosed within casing 22, which extends below pit 24. Pi-t 24 is long enough to receive substantially all of the length of jet engine 12 when platform 14 is completely lowered. The working stroke of plunger 16 is long enough to completely raise the platform to ground level 26 thereby permitting workmen standing there to work upon any selected portion of the engine. An auxiliary platform (not shown) is supported adjacent the top of rectangular pit 24 to enclose any opening existing between the engine and the side of pit 24 and permit work men to shown).

stand as close as possible to engine 12 in working upon it. Furthermore, a securing means (not shown) connects the bottom of engine 12 to platform 14 to center and secure it during use. The walls 28 and floor 30 of rectangular pit 24 are made of poured concrete. Since the engine is approximately six feet long, a working stroke in that neighborhood will permit all portions of it to be raised to working or ground level 26. This imposes severe stresses upon the extended plunger 16 which are accommodated by its unique structure as later described in detail.

A pawl and ratchet arrangement 32, which operates upon a vertical strut 34 secured to the lower side of platform 14 parallel to plunger 16, prevents the platform from being lowered unless hydraulic pressure is available for supporting the plunger. This pawl and ratchet assembly is later described in detail.

In conjunction with FIGS. 11-16 the lower end of cylinder 18 is secured to concrete foundation 36 within casing 22 through an auxiliary base plate 38 which facilitates installation of the cylinder and its removal should this become necessary. This arrangement is later described in detail in conjunction with FIG. 5.

Outer casing 22 is supported from concrete floor 30 of pit 24 by attachment to a pair of structural beams 40 which help transmit loads to the strong foundation. A support rod 42 extends upwardly from one of beams 40 to help support platform 14 and any load imposed thereon when it is in the fully lowered position. Hydraulic pressure is provided to the space between plunger 16 and cylinder 18 through oil supply line 44, and air pressure is supplied to pneumatically-operated pawl and ratchet assembly 32 through an air supply line (not A ladder 46 is provided within pit 24 to provide convenient access to the working parts within pit 24.

FIGS. 4-10 show details of plunger and cylinder assembly, and FIGS. 5, 6, 8 and particularly describe details of the plunger 16 which is remarkably strong and resistant to oscillation despite its economical structure which utilizes commercially-available materials. Plunger 16 accordingly is made from a length of standard steel tubing 47, such as that utilized in welded steel piping; and a number of slender reinforcing rods 48 are secured within tube 18 by welds 50 shown in FIG. 8 adjacent the ends of rods 48. These rods, as shown in FIG. 8, are surface roughened; and, as indicated in FIG. 8, are of the standard concrete reinforcing type. One form of suitable concrete reinforcing rod is shown in FIG. 8, and other available types of such rod with different surface designs may also be conveniently utilized. Welds 50 adjacent the ends of the tube may be conveniently made through its open ends, and they provide suflicient tensile reinforcement of the tube wall despite their end attachment. These rods 48 as shown in FIG. 10 are regularly spaced around the inner wall of tube 47 to balance their reinforcing effect upon the tube wall.

After rods 48 are secured within tube 47, an end plate 52 is welded within the bottom of plunger 16; and the tube then filled with a cementitious mixture 54 such as concrete. The upper end of plunger 16 is then sealed by an upper end plate 56 which is also welded in place. The resultant plunger 16 is remarkably strong in both tension and compression and also remarkably resistant to oscillation both in preventing its initiation and damping any small vibrations that might occur. At a full extension of approximately five to six feet, a ten-inch diameter plunger is approximately four times as stiff as a normal hollow tube, and its deflection under a given load of the type described is reduced from approximately one inch to a remarkably slight 0.060 inch deflection. Furthermore, any deflection of this small extent that occurs is quickly damped. It is believed that the concrete filler prevents the slender rods from bowing under compressive stresses as well as providing a high degree of inherent resistance to compressive loads. However, the exact mechanism by which this structure is made so remarkably stiff and resistant to vibration is not completely understood because these properties exceed all expectations.

The remarkably convenient cylinder 18 of this invention is described in FIG. 5, and it includes longitudinally aligned upper elongated tube 58 and lower elongated tube 60 which are joined together with an internal bearing ring 62 held between them. A dependable accurate metal to metal joint is provided between tubes 58 and 60 and bearing 62 by securing upper and lower flanges 64 and 66 to the top and bottom of peripheral flange 68 of hearing 62 by nuts and bolts 70. Oil leakage is prevented through this joint by O-ring seals 71 disposed within suitable sealing recesses 73 peripherally arranged about the outer surface or bearings 62.

This split arrangement for cylinder casing 18 provides several advantages in a structure incorporating a separate internal bearing. One advantage is its case of disassembly for repair of the bearing; and another is the fact that upper section 72 may be made and stocked in standard lengths with the operative stroke being adjusted for any particular installation by varying the length of lower tube 60.

The standardized upper section 72 of the cylinder also includes other functional portions such as an oil inlet 74, an upper bearing 76, and a packing gland 78 incorporating, for example, chevron packing 80. A standard wiper ring 82 is also disposed at the top of upper cylinder portion 72. Longitudinal passageways 84 are provided through bearings 62 to permit oil to flow to the lower portion of plunger 16 when it is supplied through inlet pipe 74.

Another advantage of this invention is the highly convenient means which it provides for anchoring the bottom of cyilnder 18 to a foundation. Ordinarily the bottom of the cylinder itself is embedded in concrete. However, this prevents the cylinder from being readily detached from the foundation for maintenance or complete removal. Many cylinders have, therefore, been abandoned rather than incurring the expense of difficult removal from the concrete in which they are embedded.

In accordance with this invention an auxiliary base plate 83 is provided for embedment within concrete foundation 86. It accordingly includes bent legs 88 which are permanently embedded within the concrete. A sliding centering means 90 connecting bottom plate 92 of cylinder 18 and auxiliary plate 84 is provided. Sliding centering means 90 includes a recessed pocket 94 extending downwardly from the center of plate 84 and a central boss 96 extending from the center of bottom cylinder plate 92 which is inserted to slide within pocket 94. An upwardly extending pin 98 extends also through the center of bottom cylinder plate 92 and engages a tapered recess 100 in the bottom of plunger 16 to center it during shipping and installation.

What is claimed is:

1. A cylinder comprising longitudinally aligned elongated tubes, an annular bearing for guiding a piston to slide within said cylinder, securing means connecting said tubes together with said annular bearing disposed at and overlapping their junction and extending externally of said tubes and inside of them, and sealing means at said junction for preventing leakage of fluid through it.

2. A cylinder comprising longitudinally aligned elongated tubes, an annular bearing for guiding a piston to slide within said cylinder, securing means connecting said tubes together with said annular bearing disposed at their junction end extending inside of them, sealing means at said junction for preventing leakage of fluid through it, said annular bearing incorporating a circumferential flange, and corresponding flanges being provided upon mating ends of said tubes for joining them together at said circumferential flange.

3. A cylinder as set forth in claim 2 wherein the peripheral surface of said annular bearing fits snugly within the ends of said tubes, said flanges mating in metal to metal contact for insuring accurate alignment of said tubes, and O-ring seals provided between engaging surfaces of said bearing and tubes.

4. A cylinder comprising longitudinally aligned elongated tubes, an annular bearing for guiding a piston to slide within said cylinder, securing means connecting said tubes together with said annular bearing disposed at their junction end extending inside of them, sealing means at said junction for preventing leakage of fluid through it, and passageways being provided through said annular bearing for transferring fluid from one portion of said cylinder to the other.

5. A cylinder as set forth in claim 1 wherein a second bearing is provided at the end of one of said tubes remote from said annular bearing, and the length of said portion incorporating said bearings being standardized to permit the working stroke of said cylinder to be varied merely by varying the length of the other of said tubes.

No references cited.

RICHARD B. WILKINSON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,207,046 September 21, 1965 John B. McAlpine It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 19, for "case" read ease line 36, for "cyilnder" read cylinder same column 4, after line 56, insert the following paragraphs:

The structure of cylinder 18 as described in FIGS. 4 and 5 facilitates its assembly, disassembly, installation and removal as well as making it possible to utilize a removable bearing 62. Furthermore, this readily assembled and disassembled structure facilitates the stocking of standard upper cylinder portions 72 with the overall plunger stroke for each installation being adjusted by varying the length of lower tube 60 Withdrawal of cylinder 18 from well 20 is facilitated by permanently attaching only auxiliary base plate 38 to concrete foundation 36 and providing a sliding connection between cylinder 18 and base plate 38 by the insertion of boss 96 within pocket 94. Breakable straps or tubes 102 are just strong enough to hold the parts together during installation to insure proper alignment.

Signed and sealed this 14th day of June 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A CYLINDER COMPRISING LONGITUDINALY ALIGNED ELONGATED TUBES, AN ANNULAR BEARING FOR GUIDING A PISTON TO SLIDE WITHIN SAID CYLINDER, SECURING MEANS CONNECTING SAID TUBES TOGETHER WITH SAID ANNULAR BEARING DISPOSED AT END OVERLAPPING THEIR JUNCTION AND EXTENDING EXTERNALLY OF SAID TUBES AND INSIDE OF THEM, AND SEALING MEANS AT SAID JUNCTION FOR PREVENTING LEAKAGE OF FLUID THROUGH IT. 